Process for treating cotton materials



May 21, 1940. w. H. FURNESS 2,201,262

PROCESS FOR TREATING COTTON MATERIALS Filed Dec. 9, 195a ATTORNEYj Patented May 2i, 1%

William H. Fumess, Riverton, N. J., assignor to American Rayon Company,

Inc., Riverton,

N. J., a corporation of New Jersey Application December 9, 1936, Serial No. 115,052

4 Claim.

This invention relates to tires and the cotton reinforcement thereof and to a process and solution for treating the same. The invention is also useful in connection with other mechanical rubber goods, such, for example, as belting.

One of the primary objects of the invention is to provide a tire of extended life.

More specifically it is an object to provide cotton cords, cotton cord fabric, and similar cotton reinforcements for mechanical rubber goods so treated that the hot flexing life thereof is very substantially increased over that of the untreated cotton cords and the like.

Another object of the invention is to provide a solution and a method of treatment which will 'secure the said increased hot flexing life without substantial impairment of other physical properties desirable for reinforcements of this character.

Reinforcing cotton cords are usually composed of three cabled strands, each strand being composed of five threads. Each thread is composed of fibers spun in the usual manner with ordinarily about 25 turns per inch to the left. Five of these threads are twisted into a strand with about 21 turns to the left. The three strands are twisted together with about turns per inch to the right, thus providing a balanced cord which will not unwind. (The original 25 turns imparted to each thread may be disregarded because no untwisting force of consequence is set up.)

The fibers of cotton in the natural state may be described as a hollow ribbon with kinks and crinkles and spiral turns or twists, with surface imperfections, transverse fissures, and incrustations, appearing as what might be termed striations. This is illustrated in Figure l of the accompanying drawing which shows natural cotton fibers, magnified 250 diameters.

It is the foregoing characteristics, or at least one or more of them, which cause a cotton cord such as above described to deteriorate under the flexing incident to service.

I propose to eliminate or so reduce these conditions that the flexing life is greatly increased, while at the same time securing the characteristic of maintenance of strength on elevation to temperatures at which normal cotton shows decided weakness. The cotton treated by my invention shows about the same strength as untreated cotton at room temperatures, but at high temperatures, such as are developed, for example, in service in automobile tires, the treated cotton still largely retains its strength (and regains strength on cooling) whereas the untreated cotton loses very materially in its strength.

tions.

On comparison of the fibers of this figure with the control fibers shown in Figure 1, it will be seen that the surface incrustations, fissures, striations, etc., are largely removed and the fibers are slick. It may be also that the kinks, crinkles and turns are also less pronounced. The first is certain, while the latter is not. The fibers are still ribbon-like (it will be noted in Figure 2 that one of the three fibers is shown in edge elevation) but that the hole or core space is substantially gone, the hollow ribbon being, as it were, collapsed. As compared to the untreated fibers, the treated fibers may be said to be "slick or smooth.

In bringing about the above results, I prefer to proceed as follows: I first prepare a solution containing copper sulphate, ammonia, and caustic soda and water in the following proportions: CuSO4: 51-120, 75.6 grams per liter; NH: 132

grams per liter; NaOI-I (pure), 24.2l+grams per The method liter; and water to make one liter.

apparent from what follows.

I immerse the cords, preferably in large skeins, in a bath of this solution, the volume of solution to the volume of cotton cord being substantially The ratio of copper sulphate (on the anhydrous basis) to the cellulose is just about .5 of copper sulphate to l of cellulose, by weight.

I allow the cord to remain in the solution for about two hours at room temperature (average mean temperture approximately 72 F.). The solution pressure under the foregoing conditions is sufiicient to cause the cellulose to take up copper and ammonia within the time specified. The cord should be removed from the bath before copper which it has taken up begins to leave it and return to the bath. At the ratio of copper sulphate to cellulose and with the volumes given, I find, as above stated, that the cord should be removed in about two hours.

When operating at room temperature, which,

of course, is desirable from the standpoint of cost, I find that the best results are obtained with the ratio of copper sulphate to cellulose .5 to 1, and that the limits for the solution are approximately 28% to 35% (i. e., the first solution described, diluted with 72% to water).

a lower ratio oi copper sulphate to cellulose is used, then for a treatment for the same period of time, the temperature has to be lowered. -If the ratio is increased, the time of treatment must be reduced and the temperature increased (not to exceed about 28 0.).

When the cordis removed at the end of about two hours it is immersed in a second bath just like the first one, except it is at a somewhat lower concentration than that of the first bath at the beginning of treatment. If the first bath was a of, copper to cellulose in the treated cord should 35% solution, then the second bath should preferably be about a 32% or a 33% solution. In

other words, the initial concentration of the second bath should be lower than the initial conoentration of the first bath but substantially higher than the final concentration of the first bath, i. e., when the cord is removed therefrom. This gives a solution potential for the second bath sufiicient to cause the cord to take up more copper and ammonia without the likelihood of the reversal above noted. There are other ways of securing this result as by a circulating bath, but I prefer to use two baths. Here, again, the cord is allowed to remain in the bath about two hours at room temperature and the volumes of the bath and the cord are about 30 to 1.

While the weight ratio of copper sulphate in the first bath to cellulose is preferably just about .5 to l, the cellulose has a capacity of taking up copper to the ratio of l to 1. I prefer that the ratio be about .18 to 1. At room temperature and with the volumes and concentration given, the twohour treatment in the first bath and the twohour treatment in the second bath at lower concentration, ensures that the cord, on removal from the second bath, will have a weight ratio of copper to cellulose of approximately .18 to l.

The above treatment may be said to be one giving more of a soaking effect than a solution efiect. I dissolve some of the lesser undeveloped celluloses or other more readily soluble substances which I believe cause the incrustations, striations, etc., leaving the alpha cellulose of which the bulk of the fibers is composed, substantially chemically unafiected, and softened but not dissolved.

The identity of the fibers is retained. The alteration is essentially physical. Whatever may occur, the actual fact is that fibers so treated come out as shown in the drawing. There is formed no appreciable alkali cellulose nor oxy-cellulose because the treated thread does not appear to react to dyes in the characteristic ways of alkali cellulose and oxy-cellulose. Because of the softening of the alpha cellulose, I also relieve strains due to twist, and in the subsequent setting, the cellulose is set in relieved condition. The presence of internal strains also is indicated in the natural fiber (see Fig. 1), and in the treated fiber these strains seem to be largely removed. I am not sure whether the results are to be attributed to the cleaning out of other matters from the alpha cellulose or to the relief or strains, or removal of the surface kinks, fissures, etc.

After removing the cord from the second bath I set the softened alpha cellulose by immersing v the cord in a bath having a concentration of about 50 grams sulphuric acid per liter, and approaching saturation in sodium sulphate, copper sulphate and ammonia, the said bath representing the accumulated procedure of previous washings reserved for recovery of chemicals. This bath removes some ofthe copper. The bath continues to build up in concentration of copper, am-

monium sulphate and sodium sulphate. and when this concentration becomes high enough, the bath is run oil for recovery purposes.

Following this first setting acid wash. is 'a second acidwash primarily intended to remove the remaining copper. For this bath, I preferably use a concentration of about 15 to 20 grams per liter of sulphuric acid with any desired volume in relation to the cotton cord. The important point here is that the concentration of sulphuric acid should not be high enough to hydrolize or peptize the cellulose and should not be so low that basic copper sulphate forms, the particles of which, if formed,are diiiicult to remove.

In other words, there should be enough acid to remove the balance of the copper and with sufficient acid left over to keep the copper sulphate that is in the cord and not as yet washed out, from being hydrolized into basic copper sulphate.

Now follows a waterwash which removes remaining soluble compounds carried by the cord.

The cord is now dried, at a temperature not greater than about 165 F., under tension, preferably gradually applied, restoring the cord to its original length. This tension may be adjusted to alter elongation characteristics.

When the second acid bath becomes sufilciently concentrated, it may be used to replace the first bath when the latter becomes sumciently concentrated for recovery. The acid bath arrangement' may be modified in any desired manner so long as the essential ends of the acid treatment are retained.

I prefer to prepare the starting solution as follows: I first prepare a solution of copper sulphate and aqua ammonia, preferably using a ratio of about 4 molecules of ammonia to 1 molecule of copper sulphate. This solution should contain approximately 250 grams per liter of copper sulphate. To it, I add about 1 to 2 grams per liter of sulphuric acid to inhibit hydrolization of copper sulphate and to act as a shock absorber" ii there should be any slight excess in caustic soda in the solution later to be described. I now add an aditional quantity of ammonia (a ratio of about 20 to 22 molecules to l of copper sulphate) and water.

I next prepare a solution of caustic soda, containing about 100 grams per liter. I add this caustic soda solution very slowly to the copper sulphate ammonia solution, with agitation to avoid local effects. This may be done at room temperature but as a precautionary measure it is desirable'to chill the caustic soda solution.

The solution in the proportions'first above given has a ratio of 2 molecules of caustic soda to 1 of copper sulphate, and when it is prepared as above described, the double salt of copper sulphate ammonia and caustic soda is formed, there being no appreciable free or excess caustic soda and substantially no copper hydroxide in solution, either of which I find to detrimentally affect the results.

The preferred composition of the solution and I may use other copper salts in place of the copper sulphate, such, for example, as copper nitrate, copper chloride and copper carbonate. These solutions are prepared in the same manner as above described.

I have obtained remarkable results with cotton cords for automobile tires when treated as above described. For example, tires tested in actual road tests have shown an. increase in cord body life of from to The use of cotton cords treated in accordance with the present invention is shown to be particularly advantageous in truck and bus tires run at high speeds where cord body failures are more frequent than in other types of service.

The second bath may be omitted, but if so maximum improvement will not be obtained.

I have also obtained very good results when treating the cord substantially as follows: First, wetting with a wetting agent; soaking for 30 minutes in a 360 grams per liter caustic soda so lution; then soaking for about 30 minutes in carbon bisulphide; followed by washing with sulphuric acid, 30 grams per liter, washing with water and drying at not more than F. In this particular instance the control cord stood 1980 cycles in a testing machine whereas the treated cord withstood 3994 cycles, an improvement of slightly over 100% in hot flexing life.

This is a continuation-in-part of my application Serial No. 740,030, filed August 15, 1934.

I claim:

1. A process for treating cotton materials which comprises subjecting the same to a copper sulphate, ammonia and caustic soda solution made up in the following proportions: CuSO4:5HzO, 75.6 grams per liter; NHa, 132 grams per liter; NaOH (pure), 24.21 grams per liter; and water to make one liter; said solution being diluted with water in an amount constituting from approximately 72% to 65% of the final solution; the cotton material being subjected to the said solution for a period long enough to ensure substantially complete penetration of the fibers so as to remove incrustations and striations, while leaving the alpha cellulose substantially unaffected; and then in subjecting the treated material to acid and water washes and drying.

2. A process for treating cotton materials which comprises subjecting the same to a copper sulphate, ammonia and caustic soda solution made up in the following proportions: CuSOufiHaO, 75.6 grams per liter; NHa, 132 grams per liter; NaOI-I (pure), 24.21 grams per liter; and water to make one liter; said solution being diluted with water in an amount constituting from approximately 72% to 65% of the final solution; the cotton material being subjected to the said solution for a period of about two hours to remove incrustations and striations of the fibers while leaving the alpha cellulose substantially unaffected; and then in subjecting the treated material to acid and water washes and drying.

3. The process for treating cotton materials which comprises subjecting the same to a copper sulphate, ammonia and caustic soda solution made up in the following proportions: copper sulphate, 75.6 grams per liter; ammonia, 132 grams per liter; caustic soda (pure), 24.21 grams per liter; and water, the water comprising approximately two-thirds of the solution; the material being subjected to said solution for a period long enough to ensure substantially complete penetration of the fibers so as to remove incrustations and striations, while leaving the alpha cellulose substantially unafiected; and then subjecting the treated material to acid and water washes and drying.

4.- The process of claim 3, in which after being subjected to said solution for a substantial period of time, the material is subjected to a second solution, the same as the first solution, except that the second solution is of a concentration lower than the initial concentration of the first solution but higher than the concentration of the first solution at the time of the removal of the material therefrom.

WILLIAM H. FURNESS. 

